BGP configuration help after ISP upgrade

I don't know BGP well and I've inherited this network recently. I am learning via online courses as much as possible, but this change is being required of me before I am capable/fully "trained."

My goal is to start pushing more traffic to my newly upgraded 10Gb ISP-BRAVO connection, but I don't know the way to do this yet. I could really use some help! If additional information is required, please let me know and I'll update or provide answers as requested. I've posted "sanitized" BGP/Zebra configs from each router below (linked to pastebin - is that OK on this subreddit?).

Current design:
2 dell servers running Quagga as external routers with 3-ish ISP's connected between them. Router 1(RTR1) has a 2Gb ISP circuit connected directly from ISP-Alpha over a 10Gb fiber interface. Router 2(RTR2) has two ISP's connected to it: ISP-Bravo serving us a 10Gb connection over a fiber interface and ISP-Comcastic serving us a limited-use 2Gb connection over a fiber interface.

Additionally, the routers have a single 10Gb HA/cross-over connection directly connecting each other and each also has a single 10Gb connections to an "inward-facing" HPE/Aruba 2920 switch.

The HPE/Aruba 2920 switch has 2 additional 10Gb connections that each run to separate Sophos XG550 firewalls that are configured in an HA pair.

The firewalls have four additional connections that plug into our core router/switch (2 connections from each Sophos firewall; 1 for primary user network and 1 for guest user network) and an HA link (10Gb) between them.

• ISP-Alpha has always been considered our primary network.
• ISP-Bravo has always been available for failover and spillover traffic, but was recently upgraded to 10Gb.

• ISP-Comcastic is designed to only be advertised for traffic destined for Comcast services, specifically IPTV.

• RTR1 bgpd.conf and zebra.conf: https://pastebin.com/gWqjdXg9

• RTR2 bgpd.conf and zebra.conf: https://pastebin.com/0rfZis73

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TL;DR: Based on the linked configurations, how do I force more of my users' network traffic to my newly upgraded 10Gb circuit? What would this change or new configuration look like if BGP is the way to do this?

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Sorry for such a long post - I hope this is allowable and I truly hope one or more of you can assist!